551721491 has 8 divisors (see below), whose sum is σ = 571276800. Its totient is φ = 532201600.

The previous prime is 551721473. The next prime is 551721557. The reversal of 551721491 is 194127155.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 551721491 - 2¹⁸ = 551459347 is a prime.

It is not an unprimeable number, because it can be changed into a prime (551721431) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25115 + ... + 41643.

It is an arithmetic number, because the mean of its divisors is an integer number (71409600).

Almost surely, 2^551721491 is an apocalyptic number.

551721491 is a deficient number, since it is larger than the sum of its proper divisors (19555309).

551721491 is a wasteful number, since it uses less digits than its factorization.

551721491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17709.

The product of its digits is 12600, while the sum is 35.

The square root of 551721491 is about 23488.7524360065. The cubic root of 551721491 is about 820.1752010133.

The spelling of 551721491 in words is "five hundred fifty-one million, seven hundred twenty-one thousand, four hundred ninety-one".